Notwithstanding the variety of uses to which the novel polymers of this invention can be put, their use as semipermeable membranes is of current interest and shall accordingly be noted herein. Semipermeable membranes comprising polyarylenes containing a variety of substituent groups and the process for their preparation have been set forth in several patents, owned by the Assignee of record herein, and include U.S. Pat. Nos. 4,586,939, 4,521,224 and 4,596,860. Unlike the inventions disclosed in those applications, the present invention provides for the synthesis of additional substituted polymers and via a novel process empolying phase transfer catalysis.